Safety assessment for dams of the cascade reservoirs system of Lancang River in extreme situations

Abstract

Numerous dams have been constructed in the midstream and downstream regions of Lancang River, which form a complex cascade reservoirs system. The safety of dams is critical for water resource management of the whole system. To check the safety of dams, this study used the MIKE 11 model to simulate flood routing along the Lancang River from Xiaowan dam to Jinghong dam under extreme situations of 100-, 500-, 1000-, 5000-, and 10,000-year design floods throughout the whole cascade reservoirs system. The design flood events used as the input for the MIKE 11 model contains the design flood hydrograph of the upstream reservoirs and corresponding flood hydrographs of the intermediate areas. The design flood hydrograph of the upstream reservoirs was obtained using the Equal Frequency Factor Method, and the corresponding flood hydrograph of the intermediate areas was obtained using the Equivalent Frequency Regional Composition Method. The results show that all dams are safe for the 100-, 500-, 1000-, and 5000-year design flood situations throughout the whole cascade reservoirs system, whereas the Manwan and Jinghong dams have a risk of overtopping under a 10,000-year design flood. The curves showing the relationship between the highest water level and return period for the dams are also presented.

Keywords

Notes

Acknowledgments

This study was supported by the National Natural Key Technology R&D program of the ministry of Science and Technology of China (2013BAB06B01), the Major Program of the National Natural Science Foundation of China (Grant No. 51190095), and the Special Funds for Public Industry Research Projects of the China Ministry of Water Resources (201401034, 201501004). The authors would like to thank Huaneng Lancang River Hydropower Company for providing hydrologic and topographical data. The authors are also grateful to the editors and the anonymous reviewers for their constructive comments that led to considerable improvements of the paper.